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Programmed DNA Degradation and Nucleolar Biogenesis Occur in Distinct Organelles During Macronuclear Development in Tetrahymena
Author(s) -
SMOTHERS JAMES F.,
MADIREDDI MALAVI T.,
WARNER FRED D.,
ALLIS C. DAVID
Publication year - 1997
Publication title -
journal of eukaryotic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 1066-5234
DOI - 10.1111/j.1550-7408.1997.tb05942.x
Subject(s) - nucleolus , biology , tetrahymena , organelle , microbiology and biotechnology , biogenesis , dna , ribosomal dna , somatic cell , genetics , gene , phylogenetics , nucleus
. Programmed DNA rearrangements, including DNA degradation, characterize the development of the soma from the germline in a number of developmental systems. Pddl p (programmed DNA degradation 1 protein), a development‐specific polypeptide in Tetrahymena , is enriched in developing macronuclei (anlagen) and has been implicated in DNA elimination and nucleolar biogenesis. Here, immunocytochemistry and fluorescent in situ hybridization (FISH) were employed to follow Pddl p and two nucleolar markers (Nopp52 and rDNA) during macronuclear development. Both Pdd 1p and Nopp52 localize to subnuclear structures, each of which resemble nucleoli. However, while true nucleoli form and persist during development, Pdd 1p‐positive structures are only present for a brief period of macronuclear differentiation. Accordingly, two distinct organelles can be recognized in anlagen: (1) Pdd 1p‐positive structures, which lack Nopp52 and rDNA, and (2) developing nucleoli which contain rDNA and Nopp52 but lack Pdd 1p. Taken together with recent data corroborating Pdd 1p's role in DNA elimination, we favor the hypothesis that Pdd 1p structures are unique, short‐lived organelles, likely to function in programmed DNA degradation and not in nucleolar biogenesis.